The present invention relates to an expansible plug for anchoring in conically inwardly expanding drilled holes.
More particularly, it relates to such an expansible plug which has a multi-slotted expansive anchor having an inner opening and a mounting object, and an expander body arranged at the bottom of the drilled hole.
Expansible plugs of the above mentioned general type are known in the art. One of such expansible plugs is disclosed, for example, in the German document DE 3,117,581 A1. Here the expansible plug has a multi-slotted expansion anchor with an inner opening and an expander body which is is held by a peg engaging in the inner opening in the front part of the expansion anchor. For anchoring the expansible plug is driven into a drilled hole of a concrete part provided with an undercut, until the expander body abuts against the bottom of the drilled hole. Since the total length of the expander body substantially corresponds to the length of the undercut of the drilled hole, the front end edge of the expansion anchor after its insertion into the drilled hole is located substantially at the height of the transition between the cylindrical part of the opening and the undercut. During driving-in of the expansion anchor the expansion segments are pressed radially outwardly by the expander body so that a substantial friction and clamping of the expansion segments at the transition edge from the cylindrical portion of the drilled hole to the undercut occurs. This leads to an increase of the impact energy and to a breakage of the drilled hole in the region of the transition edge. Therefore both the slipping properties of the plug and also its pull-out value are adversely affected.